Modified hull form



Nov. 22, 1960 e. G. EDDY 2,960,957

MODIFIED HULL FORM Filed lay 7, 1957 IN V EN TOR. 6 60/:96 6. E do y flTTORNEY United States Patent MODIFIED HULL FORM George G. Eddy, 141 State 'Park Drive, Bay City, Mich.

Filed May 7, 1957, Ser. No. 657,602

1 Claim. (Cl. 11456) This invention relates to a novel hull form and is more particularly concerned with a hull form having the advantages of both a conic and planing shape.

A truncated conic shape of hull form is known to be the most efficient form for driving through a fluid with a maximum weight load and a minimum horsepower. But, although it is the most eificient for driving purposes, such a form is almost completely lacking in athwartship stability. On the other hand, the conventional planing or semi-planing hull form offers considerable athwartship stability, but does not ofler the weight-horsepower advantages above a certain ratio that is inherent in the truncated conic shape.

It is, therefore, a principal object of the present invention to provide a hull form combining the advantageous driving characteristics of a truncated conic hull with the stability of a planing hull at and above a predetermined weight-horsepower ratio. Another object of the present invention is to provide a hull easily driven and stable at both low and high Weight-horsepower ratios.

Still a further object of the present invention is to provide a hull having a bottom, a portion of which is a truncated conic shape and a portion of which is a planing surface.

Another object of the present invention is to provide a hull form comprising a transom, sides joined together to form a bow at the end opposite the transom and a fluidcontacting surface including a truncated conic portion and outward from said conic portion a planing surface intersecting the sides. Other objects will become apparent hereinafter.

The foregoing and additional objects have been accomplished by the provision of a hull form described in the accompanying drawing which is given for the purposes of illustration only and not to be construed as limiting the invention thereto, and in which:

Fig. 1 is a perspective view of the bottom of the hull form of the present invention;

Fig. 2 is a section of the hull form of the present invention taken at 22 of Fig. 1;

Fig. 3 is a section of the hull form of the present invention taken at 33 of Fig. 1;

Fig. 4 is a section of the hull form of the present invention taken at 4-4 of Fig. 1;

Fig. 5 is a truncated cone used to illustrate the principle of a portion of the hull form of the present invention; and Fig. 6 is a typical semi-planing hull form used to illustrate the principle of a portion of the hull form of the present invention.

Referring now to the drawing at Fig. 5, if a hull is designed where a substantial portion of its fluid-contacting surface comprises such a truncated cone shape, with the apex at the bow and the thickest section at the stern, a minimum of horsepower is required to move such a shape through the fluid at a predetermined speed and weight load when compared with conventional hull forms.

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However, practically no athwartship stability is available if only the truncated cone is used as the fluid-contacting surface. Alternatively, a flat bottom or substantially flat bottom hull form as illustrated in Fig. 6 gives a high degree of athwartship stability but requires considerably more horsepower to achieve a predetermined speed at a fixed weight load factor.

Combining these two forms of hull design into a single hull as illustrated in Fig. 1 has produced a hull form giving the advantages of both types of hull design. A minimum of horsepower to achieve a predetermined speed at a particular load factor, and acceptable athwartship stability are obtained. As illustrated in Fig. 1, a transom 7 and sides 8 extending from the transom to an intersecting point at the how 9 are provided. Starting at the bow and proceeding rearward is a truncated conic portion 10 and extending from said truncated conic portion 10 to the sides 8 is a planing or semi-planing surface 11 running from the how 9 to the transom 7. While the above comprises a general description of the present invention, it is to be understood that various deviations from the specific design shown are contemplated within the scope of this invention, including a planing surface for only the rearward half or one-third of the hull form while the forward half or two-thirds of the fluid contacting surface is of a truncated conic shape. Similarly, it is contemplated that the truncated conic fluid-contacting surface with its apex at the bow and proceeding rearwardly could be merged into a conic section tapering rearwardly, the intersection of the two conic sections occurring %s to %s of the length of the hull from the bow.

To determine the amount of conic area to be employed, it is desirable to provide that area which is equal to the area of fluid displaced at a predetermined speed, horsepower and weight ratio. Thus, the amount of conic area, if substantially smaller than this amount, would require an excessive amount of horsepower for driving, while if substantially greater, would give an athwartship instability.

The hull form of the present invention, then, provides excellent athwartship stability with desirable driving characteristics, and, in addition, does not have the usual planing hull detraction of skidding on turns or sliding in a beam wind, but rather, gives good control on turns and good slide resistance in beam winds.

Various modifications may be made in the hull form of the present invention without departing from the spirit or scope thereof, and it is to be understood that I limit myself only as defined in the appended claim.

I claim:

A hull form comprising a transom, sides, and a fluidcontacting surface consisting of a downwardly-projecting, truncated conic portion extending substantially the full length of said fluid-contacting surface, the apex of said truncated conic portion being located at the how, the amount of said truncated conic portion being equal to the fluid displaced at a predetermined speed, horsepower and weight ratio for said hull form, and outward from said conic portion a substantially flat planing surface transecting said sides.

References Cited in the file of this patent UNITED STATES PATENTS 1,189,227 Baker July 4, 1916 2,249,958 Inwood July 22, 1941 FOREIGN PATENTS 23,861 Great Britain 1894 29,895 Great Britain 1910 

